Wood River times. [volume] (Hailey, Idaho) 1882-1915, 1887-12-13


Member of the American Institute of
Mining Engineers
TYPOGRAPHICAL AND GEOLOGICAL.
The Wood River region covers an
area of 1000 or 5000 square miles, is
drained by Wood River, and lies at
an altitude of from 5000 to 1000 feet.
Bellevue, at the former elevation, and
the higher altitude about Gslena at
the latter. 1t is essentially region
of mountains and canyons. The coun-
try rock is almost entirely very sill
cious limestone. Professor Jenney
informs me that the limestones rest
directly upon granite, with a few
known exceptions, where there are
intermediate quantities., etc. The ge-
ology is thus quite simple. Some
granite fosses and dykes rise through
the limestone at certain points, and
porphyrltic eruptive rocks are not I'M
common. The Professor describes the
metamorphic limestone strata as being
at least 10000 feet thick, and very
possibly 10000. There is little or no
evidence to show their age, although
from certain fossils discovered, it is
surmised to be lower Silurian. How
ever, by the limestones resting upon
the granite in certain districts, there
is room for the surmise that the former
are older than the Cambrian age.
Still, this is only surmise, and as such
hardly worthy of printing.
The immediate valley Of Wood
River is filed to quite distance with
lava of the same sort as covers the
Snake river plains, and it is doubtless
of the same outflow. There are some
appearances to show that the source
of a large part of the lava which
covers so much of Southern Idaho
was in assures in the Wood River
mountains. This hypothesis is
strengthened by the appearance of
the several mountains, which prove
former volcanic activity, one in par
ticular, which was an active volcano
vent, the crater of which was broken
down at one side, and the now solidi-
Ged lava which was flowing over re-
mains to tell the geological story.
These lava flows have little or nothing
to do with mining, except that veins
may be faulted by the dykes or hid
den by the outhows. Glacial forces
have also been active, and at time
presumably wholly subsequent to vol
canic activity, although Professor
Jenney speaks confidently of lavas
which are so new as not t. be covered
by moss. The general drift extends
somewhat below Bellevue, where it
overspreads the lava fields, and higher
up, even with the town, it forms fine
terraces, which become higher as we
proceed up the river. The valley is
beautifully terraced for long way
into the mountains and exhibits finely
the result of glaciation and river de-
mutation. Some Of the tributaries
likewise show the same. The charac-
ter of the drift is much like that in
the lower Willamette valley, being
composed of leveled deposits OF
rounded boulders of moderate size, in
the interstices of which coarse sand is
found. | noted no cratic blocks such
as abound on high hillsides in glaci
ated districts.
THE VEINS.
Unlike most deposits in limestone
the lodes of Wood River are largely
perhaps wholly, veins with walls anc
all the other concomitants of ordlnar,
veins. In purer limestones, as IL
those of Eureka, Nevada, the ten
dency of ores is to group themselves
in chambers or a succession of cham
bers of irregular shape, usually with
out perceptible vein structure. Sucl
E deposits may be wholly unconnectet
with each other, but in majority o
instances narrow layer of "gouge'
passes from one to the other, marking
perhaps the course of the assure whic
: admitted the solutions which brough
the ores and deposited them. Littl
indication cf this state of things exist
at Wood River, 1t is said, the ten
dency to ordinary vein structure belni
almost universal there. The Parke
mine, on a vein which has been we
studied by Professor Ienney (who,
may remark, is one of the most pre-
found of geologists and skillful c
mining ergineers), is case in poln
e | am informed by the gentleman tina
the vein matter is quartz, carry 10
bodies OF very rich galena at inteI
{ walls, the width of vein remainin
Il fairly constant, while the valuabl
f contents come and 90. From tn
e mine over 100000 have been take
in the several. years of its working
and two thirds Of this were profit
I hope to present the exact figures {
d production at some future time, the
:. having been promised me by Messr
Jenney and Watt, the principal o
IS ficers of the Parker Mining Compan
. Tho mine is fairly a representative